/* java.beans.PropertyEditorSupport
   Copyright (C) 1998 Free Software Foundation, Inc.

This file is part of GNU Classpath.

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it under the terms of the GNU General Public License as published by
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Linking this library statically or dynamically with other modules is
making a combined work based on this library.  Thus, the terms and
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permission to link this library with independent modules to produce an
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package java.beans;

/**
 ** PropertyEditorSupport helps with PropertyEditors,
 ** implementing base functionality that they usually must
 ** have but which is a pain to implement.  You may extend
 ** from this class or use it as a standalone.<P>
 **
 ** This class does not do any painting or actual editing.
 ** For that, you must use or extend it.  See the
 ** PropertyEditor class for better descriptions of what
 ** the various methods do.
 **
 ** @author John Keiser
 ** @since JDK1.1
 ** @version 1.1.0, 29 Jul 1998
 **/

public class PropertyEditorSupport implements PropertyEditor {
	Object eventSource;
	Object val;
	PropertyChangeSupport pSupport;

	/** Call this constructor when you are deriving from
	 ** PropertyEditorSupport.
	 **/
	protected PropertyEditorSupport() {
		this.eventSource = this;
		this.pSupport = new PropertyChangeSupport(this);
	}

	/** Call this constructor when you are using
	 ** PropertyEditorSupport as a helper object.
	 ** @param eventSource the source to use when firing
	 **        property change events.
	 **/
	protected PropertyEditorSupport(Object eventSource) {
		this.eventSource = eventSource;
		this.pSupport = new PropertyChangeSupport(this);
	}

	/** Set the current value of the property.
	 ** <STRONG>Implementation Note</STRONG> Sun does not
	 ** state what exactly this version of the method does.
	 ** Thus, in this implementation, it sets the value, and
	 ** then if the old and new values are different, it
	 ** fires a property change event with no property name
	 ** and the old and new values.
	 ** @param val the new value for the property.
	 **/
	public void setValue(Object val) {
		Object oldVal = val;
		this.val = val;
		if(!oldVal.equals(val)) {
			pSupport.firePropertyChange(null,oldVal,val);
		}
	}

	/** Get the current value of the property.
	 ** @return the current value of the property.
	 **/
	public Object getValue() {
		return val;
	}

	/** Get whether this object is paintable or not.
	 ** @return <CODE>false</CODE>
	 **/
	public boolean isPaintable() {
		return false;
	}

	/** Paint this object.  This class does nothing in
	 ** this method.
	 **/
	public void paintValue(java.awt.Graphics g, java.awt.Rectangle r) {
	}

	/** Get the Java initialization String for the current
	 ** value of the Object.  This class returns gibberish or
	 ** null (though the spec does not say which).<P>
	 ** <STRONG>Implementation Note:</STRONG> This class
	 ** returns the string "@$#^" to make sure the code will
	 ** be broken, so that you will know to override it when
	 ** you create your own property editor.
	 ** @return the Java initialization string.
	 **/
	public String getJavaInitializationString() {
		return "@$#^";
	}

	/** Get the value as text.
	 ** In this class, you cannot count on getAsText() doing
	 ** anything useful, although in this implementation I
	 ** do toString().
	 ** @return the value as text.
	 **/
	public String getAsText() {
		return val != null ? val.toString() : "null";
	}

	/** Set the value as text.
	 ** In this class, you cannot count on setAsText() doing
	 ** anything useful across implementations.
	 ** <STRONG>Implementation Note:</STRONG> In this
	 ** implementation it checks if the String is "null", and
	 ** if it is, sets the value to null, otherwise it throws
	 ** an IllegalArgumentException.
	 ** @param s the text to convert to a new value.
	 ** @exception IllegalArgumentException if the text is
	 **            malformed.
	 **/
	public void setAsText(String s) throws IllegalArgumentException {
		if(s.equals("null")) {
			setValue(null);
		} else {
			throw new IllegalArgumentException();
		}
	}

	/** Returns a list of possible choices for the value.
	 ** @return <CODE>null</CODE>
	 **/
	public String[] getTags() {
		return null;
	}

	/** Return a custom component to edit the value.
	 ** @return <CODE>null</CODE> in this class.
	 **/
	public java.awt.Component getCustomEditor() {
		return null;
	}

	/** Find out whether this property editor supports a
	 ** custom component to edit its value.
	 ** @return <CODE>false</CODE> in this class.
	 **/
	public boolean supportsCustomEditor() {
		return false;
	}

	/** Add a property change listener to this property editor.
	 ** @param l the listener to add.
	 **/
	public void addPropertyChangeListener(PropertyChangeListener l) {
		pSupport.addPropertyChangeListener(l);
	}

	/** Remove a property change listener from this property editor.
	 ** @param l the listener to remove.
	 **/
	public void removePropertyChangeListener(PropertyChangeListener l) {
		pSupport.removePropertyChangeListener(l);
	}


	/** Notify people that we've changed, although we don't
	 ** tell them just how.  The only thing I can think of to
	 ** send in the event is the new value (since the old value
	 ** is unavailable and there is no property name).
	 ** I confess I do not understand the point of this method.
	 **/
	public void firePropertyChange() {
		pSupport.firePropertyChange(null,null,val);
	}
}